Stacking machines which build the stack from the bottom have long been known. U.S. Pat. No. 2,488,674 issued Nov. 22, 1949 to Clifton S. Mallott, Jr. is an example of such a stacker. U.S. Pat. No. 3,568,860 issued Mar. 9, 1971 to Phillip G. Rollins and U.S. Pat. No. 3,861,538 issued Jan. 21, 1975 to Yakov Duchinsky et al are other examples of bottom stackers. These machines use a series of fingers to temporarily support a stack while an article is added beneath the stack. After the article to be added is in place the fingers are withdrawn from the bottom of the stack permitting it to fall on the newly added article. The withdrawal of the fingers is accomplished by sliding the fingers along the last previously stacked article and the sliding movement of the fingers results in frictional relative contact between the stacking fingers and the bottom most article in the stack.
Such frictional abrasion is sometimes objectionable as when the weight of a stack of fragile articles such as lacework or fragile loosely woven or non-woven goods or fragile paper articles coupled with frictional relative movement damages the stacked articles. An example of such articles is the disposable paper sleeves worn by members of the staff in some operating rooms.